Rechargeable lithium batteries operating at room temperature offer several advantages compared to conventional aqueous technologies. These advantages include higher energy density (up to 150 watts-hours per kilogram), higher cell voltages (up to about 4 volts per cell), and longer charge retention or shelf life (up to 5-10 years). These advantages result in part from the high standard potential and low electrochemical equivalent weight of lithium.
An alternative to liquid electrolytes in lithium cells is a solid polymer electrolyte formed by incorporating lithium salt into polymer matrices and casting into thin films. These polymers can be used as both the electrolyte and separator. They have lower conductivities and lower lithium-ion transport numbers than the liquid electrolytes but are less reactive with lithium, which should enhance the safety of the battery. Much research has been devoted to the creation of lithium-polymer batteries. The objective of this effort, as with any battery program, is to develop batteries which have high energy density, high power density, good cycle life and charge retention, and provide this high performance reliably and safely. Of course, the advantageous characteristics of lithium cells are all for naught if the battery materials cannot be packaged properly. The foil packaging and flimsy tabs currently employed with lithium polymer cells are not sufficiently durable to make for a robust consumer product. Therefore, there is a need for improved packaging and tabs for lithium polymer cells.